Final answer:
Early Christianity spread through disciples and missionaries, including prominent figures like St. Paul, and was facilitated by the conversion of Roman officials such as Constantine. Merchants and sailors also played a role in its expansion to new regions.
Step-by-step explanation:
Early Christianity spread from the Middle East into Europe primarily through disciples and missionaries. These figures carried the teachings of Jesus and established Christian communities in various cities across the Roman Empire, including major centers such as Alexandria. Additionally, Roman officials and the broader populace, including slaves, were increasingly attracted to the religion's promises of eternal life and forgiveness.
One of the most prominent figures in early Christian spread was St. Paul, who, after a profound conversion experience, became a passionate evangelist for the religion. The support of secular rulers also played a role; for example, after the Roman Emperor Constantine's miraculous conversion to Christianity, the faith became legally acceptable and later the official state religion under Theodosius. Furthermore, the process of Christianization often involved the pragmatic integration of pagan practices into Christian worship, making it more palatable to converts.
Merchants and sailors also contributed to the diffusion of Christianity by bringing the religion to new areas, including the African kingdoms. Christianity's spread was not strictly a top-down process but also occurred through cultural diffusion and commercial exchanges as exemplified in the conversion of the kingdom of Aksum, traditionally attributed to the Syrian teacher Frumentius.